Combustion apparatus and control system therefor



July 6, 1965 w. G. SEE ETAL 3,192,920

COMBUSTION APPARATUS AND CONTROL SYSTEM THEREFOR Filed Sept. 3, 1963 5 Sheets-Sheet 1 I uvmvrons: H 52 48 BXWALTER 6. SEE

ARTHUR WILLIAMS av I ATT'YS July 6, 1965 w. G. SEE ETAL 3,192,920

COMBUSTION APPARATUS AND CONTROL SYSTEM THEREFOR Filed Sept. 3. 1963 5 Sheets-Sheet 2 INVENTORSI WALTER 6. SEE ARTHUR WILLIAMS M I 6 ATT'YS y 1965 w. G. SEE ET AL 3,192,920

COMBUSTION APPARATUS AND CONTROL SYSTEM THEREFOR Filed Sept. 3, 1963 5 Sheets-Sheet 3 7/ INVENTORS WALTER (5. SEE ARTHUR WILLIAMS BY 4% I 6 M ATT'XS;

July 6, 1965 w. G. SEE ETAL 3,192,920

COMBUSTION APPARATUS AND CONTROL SYSTEM THEREFOR Filed Sept. 3, 1965 5 Sheets-Sheet 4 FIG. 9 ,I0

Ill

INVENTORS: WALTER 6. SEE ARTHUR WILLIAMS B I I ATT'YS July 6, 1965 3,192,920

COMBUSTION APPARATUS AND CONTROL SYSTEM THEREFOR Filed Sept. 3, 1963 w. c. SEE ETAL 5 Sheets-Sheet 5 on I mw INVENTORS'. WALTER 6. SEE

ARTHUR WILLIAMS ATT'YS United States Patent 3,192,920 COMBUSTION APPARATUS AND CONTROL SYSTEM THEREFOR Walter G. See, Crown Point, and Arthur Williams, Munster, Ind, assignors to Submerged Combustion, Inc., Hammond, Ind, a corporation of Indiana Filed Sept. 3, 1963, Ser. No. 305,955 6 Claims. (Cl. 126360) This application is a continuation-in-part of our copending application Serial No. 731,823, filed April 29, 1958 and our application Serial No. 192,768, filed May 7, 1962. The present application is also directed toward subject matter which was required to be divided from said appplication Serial No. 192,768.

This invention relates to a liquid heatingapparatus and/or evaporating apparatus in which heat is supplied to a body of liquid by direct contact with hot combustion gases and also by indirect heat exchange between the liquid and the walls of hollow members conveying the hot combustion gases to a point or points of discharge into the liquid.

One of the primary objects of this invention is to provide highly efficient apparatus for the heating of liquids.

Another primary object of this invention is to provide liquid heating apparatus capable of highly efiicient heat transfer of the heat of hot combustion gases into the body of liquid.

Another object of the invention is to provide improvements in water heating vessels.

A further object of the invention is to provide improvements in evaporating vessels. These, and other objects and advantages of the invention hereafter described or made apparent to those skilled in the art, may be attained by utilizing the principles of the invention described hereafter with respect to specific embodiments of the invention illustrated in the accompanying drawings where- FIG. 1 is a side elevation of a water or other liquid heating apparatus with a portion thereof broken away to facilitate the illustration of the embodiment;

FIG. 2 is a top plan view of the embodiment of FIG. 1 with a portion thereof broken away to facilitate the illustration of the embodiment;

FIG. 3 is a sectional view taken on section 3-3 of FIG. 2;

FIG. 4 and FIG. 5 are side and rear elevations, respectively, of combustion gas distributing means used in the embodiment of FIGS. 1 and 2;

FIG. 6 is a cross-sectional view taken on sections 6--6 of FIG. 5;

FIG. 7 is a fragmentary view of the side elevation of a modified form of the apparatus of FIGS. 1 and 2;

FIG. 8 is an end elevation of another embodiment of the invention especially adapted to be used as an evaporating vessel;

FIG. 9 is a side elevation of the embodiment of FIG. 8;

FIG. 10 is a side elevation of another embodiment of the invention especially adapted to be used in the heating of water or other liquid;

FIG. 11 is an end elevation of the embodiment of FIG. 10;

FIG. 12 is a diametric cross-section through a dual submerged combustion burner which can be used in the apparatus of FIGS. 1 through 11;

FIG. 13 is a diagrammatic view of an air and gas flow control which may be used in conjunction with the burner of FIG. 12 in the practice of the invention;

In FIGS. 1 through 6 there is shown apparatus which is especially adapted for the heating of water or other liquid by means of direct contact between hot gases of combustion and the liquid. This apparatus comprises a tank 1,

"ice.

which is relatively shallow in relation to its length and width. The rectilinear tank 1 is made of an end wall 2 having in its upper corner an outlet pipe 3 for the heated water or other liquid. The top of the tank 1 is closed by a top wall 4 extending thereacross. The top wall 4 is shorter than the bottom wall 5. The remaining walls of the tank 1 are the side walls 6 and 7. These walls form a wa-teratight, liquid-holding tank with a riser section or tower section 8 at the end of the tank 1 remote from the outlet pipe 3; The riser section or towersection 8 is of a width coextensive with the width of the tank 1 and is made up of an end wall 9, which also is the end wall for the tank 1, together with end wall 16 and slide walls 11 and 12. The top of the rectilinear riser section or tower section 8 is closed by a cover plate 13 through which ex-.

tends a vapor outlet pipe 14 having a flange 15 for use in connection of the outlet pipe 14 to vapor and gas-conveying piping (not shown).

The end wall 10 has a manhole tube 16 thereon. This manhole tube is closed by removable cover plate 17. The purpose of the manhole tube is to allow operating or maintenance personnel toenter the tank 1 for purposes of cleaning, repair or the like.

There is mounted in the top wall 4 a burner uni-t 18-of the submerged combustion variety. The burner shown in FIGS. 1 and 2 is a dual combustion burner of the type illustrated in FIG. 12, which will be described in detail hereinafter. .The burner plates 19 of the burner unit- 18 discharge a fuel gas and air or oxygen gas into the combustion chamber 20. It will be noted that the combustion chamber 20 has a flange 20a which is secured to a flange 20b on the outside of the burner and surrounds the lower part of the burner in spaced relation thereto. The combustion chamber 20 extends beyond the burner plates 19. The hot combustion gases are discharged through an opening 21 in the end wall of the combustion chamber 20 into a cylindrical leg 22 of the burner unit. The opening 21 is of sufliciently small size to provide a back pressure in said combustion chamber when said burner is in operation.

Thereafter, the hot gases flow from the cylindrical leg 22 into a gas outlet tube 23 extending across the lower portion of tank'l. This gas outlet tube 23 is positioned near the end of the tank 1 remote from the tower section 8. The gas outlet tube 23 is supported on the bottom wall 5 of the tank 1 by support plates 24 attached to the bot tom wall 5.

The gas outlet tube 23 is illustrated in detail in FIGS. 5 and 6. It comprises an outer tube 25 'rotatably sup ported about an inner tube 26. The tubes 25 and 26, re spectively, have gas outlet ports 27, 28in their lower sides. These ports can be brought into any desired degree of alignment by rotation of the tube 25 about: tube 26 by means of pressure against the post 29.fixedly mounted on the tube 25. This adjustable positioning of. the ports 27, 28 permits the adjustment of the effective area of the gas outlet ports for a purpose later described.

Water or other liquid to be heated is admitted to the heating unit through the inlet pipe 30 located in the upper portion of the side wall 12 of the tower section 8. Heated water, on the other hand, is discharged through the outlet pipe 3 located in the corner of the end wall 2. The corner of the tank 1 from which the heated water is discharged is divided from the rest of the tank by a diagonal corner plate 31. The corner plate 31 contains near its lower end a series of ports 32 which communicate the triangular corner compartment and the main body of the tank 1. The'corner compartment has a temperature sensing probe 33 therein, which probe is connected by' cable 34- to an automatic temperature controller 35. The temperature controller 35, in turn, controls the quantity of fuel gas and air or oxygen gas supplied to the burner so that a substantially level temperature is maintained in the heated liquid discharged from the heating apparatus.

The water supply unit in the tower 8 comprises a coupling 35 attached to the inlet pipe 39. A series of three branch, distributing pipes 37, 38, 39 are mounted in the coupling 36. Each of these branch pipes has a'right elbow 48 at its outer end wit-h short vertical pipes 41 depending downwardly from the elbows 40. Water admitted to the heating vessel is discharged from the three pipes 41, which are located near the gas and vapor outlet pipe 14. The water falls through the warm gases rising in the tower section 8. If desired, the outlet pipes '41 may be provided with coarse spray nozzles to increase the contact between the water and the rising gases so that there is a greater transfer of the residual heat in the rising gases to the descending water. "in: sprays are ordinarily to be avoided because of the tendency of the entrainment of mist in the gases emitted through the outlet pipe 14.

Fuel gas is supplied to the burner through the fuel gas main supply pipe 42, which has a shut-off valve 43 and a gas pressure regulator 44. The main supply pipe 42 is branched into an inner burner gas supply pipe 45 and an outer burner gas supply pipe 46, each of which is connected to a distributing head in the gas burner. The details of the gas burner will be described hereinafter with particular reference to FIG. 12.

Each of the gas supply pipes 45 and 46 have manually operable shut-off valves 48 by which gas flow can be shut off .to either or both of the inner burner distributor head 49 or outer burner distributor head 50. The inner burner gas sup-plypipe 45 has a small branch pipe 52 by which gas is supplied to the pilot tube distributing head 51 of the combustion burner.

For economical reasons, it is usually preferable to use air as the combustion supporting gas. Accordingly, the heating vessel of the invention has an air blower-compressor 53 mounted on the top wall 4 of the tank 1. The blower-compressor is driven by an electric motor 54. The air is discharged from the blower-compressor 53 through the main air supply pipe 55 to the distributing head of the outer burner. A portion of the air in pipe 55 fl ws through branch pipe 56 to the distributing head of the inner burner and a small portion of the air flowing through branch pipe 56 flows through branch pipe 57 to the distributing head of the pilot burner.

One of the important features of the apparatus of this invention is in the burner turn down control system by which the amount of gas supplied to the outer burner and the amount of air supplied to the outer burner is accomplished at predetermined, variable ratios. This aspect of the invention is provided by a butterfly valve 58 in the main air supply pipe 55 and a butterfly valve 59 in the main gas supply pipe 46, both of which pipes are connected to the distributor head for the outer burner. The butterfly plates of each of the butterfly valves are rotated by link arms 60 and 61 for the valves 58 and 59, respectively. Link arms 66 and 61 are connected by a connecting link arm 62 pivotally connected to the ends of each of the arms 60 and 61. These interlinked arms are, in turn, connected by a pivot link 63 to a rotatable arm 64 of a reversible motor 65. The motor 65 is controlled by known means by the temperature regulator 35. The electrical connection between the temperature controller 35 and the reversible motor 65 is shown symbolically by the arrows on these members in FIG. 1.

It will be noted from FIG. 2 that the link arm 60 for the butterfly valve 53 in the main air supply pipe 55 is longer than the link arm 61 of the butterfly valve in the main gas supply pipe 46. The purpose of these link arms of greater length is to provide a diiferent degree of rotation of the butterfly plates in the valves 58 and 59 when the arm 64 is rotated by the motor 65. It has been found that the outer burner cannot be turned down from its maximum gas and air flow by equally proportionate decreases of the air and gas fiow through the outer burner without encountering a rough or hanging operation. For example, it has been found in the operation of the dual combustion burner that when the fuel gas flow is turned down to a flow of 40% of the maximum flow of gas through the outer burner, the air flow cannot be decreased to 46% of the maximum air flow without encountering a rough or banging operation. In order to have a smooth outer burner operation, the air must be decreased in the order of only about 70% of the maximum air flow of the outer burner when the gas flow is turned down to a value of 40% of the maximum gas flow. in order to maintain sufficient velocity at the orifices of the burner plate to prevent the encountering of the rough or banging operations.

Therefore, the link arm $6 is proportionately longer than the link arm 61 so that a given amount of movement of the link arm 63 by the motor arm 64 causes the butterfly plate of the valve 58 to rotate a lesser degree of angular rotation than the rotation of the butterfly plate of the valve 59. Thus, the turn down or turn up of the outer burner by adjustment of the butterfly valves via the mechanical linkage is done under conditions wherein there is a lesser amount of turn down in the air supply than in the gas supply during burner turn down and a greater amount of turn up in the outer burner gas supply than in the outer burner air supply during burner turn up.

The foregoing burner turn up and turn down mechanism is especially useful in burners which operate under discharge of gases into the body of liquid through orifices having a constant size opening, e.g., the tube 26 without the rotatable outer tube 25 thereon. Where, however, means is provided to partly close the gas discharge holes or orifices when the burner is turned down and to open the holes or orifices when the burner is turned up in direct proportion to the change in combustion gas supply resulting from the turn down or turn up, i.e., the tube structure illustrated in FIGS. 5 and 6, the outer burner can he turned down or turned up under conditions of equally proportionate changes in the air-gas supply rate. With a burner operating under automatic temperature control, it is usually more feasible to use a structure having the mechanical linkage illustrated in FIGS. 1 and 2 for turning down or turning up the outer burner along with a gas discharge tube 26 having constant size orifice openings.

The gas supply pipes 45 and 46 have a pressure regulator as therein for maintaining the desired gas pressure. The control panel 67 is mounted on the tank 1. It contains the control buttons for activating and deactivating motor 54, pressure gauges, and other instrumentation and controls for operating the combustion burner.

Thus, it will be seen that the apparatus of FIGS. 1 through 6 is especially suitable for the heating of water to a predetermined temperature by direct heat exchange between hot combustion gases and the water, or other liquid, if desired. The burner control system is one in which the quantity of combustion gas output can be controlled automaticaily in relation to the temperature of the Water or other liquid being heated. The function of the tower section 8 is one of containing substantially any entrained water rising with the hot combustion gases out of the liquid being heated. The height to which the en trained drops rise in a given heating apparatus under maximum combustion gas output can be determined under operating conditions. It is considered the best practice to make the height of the tower 8 18 to 24 inches greater than the highest rise of entrained liquid. The release of hot combustion gases is done in the portion of the tank under the plate 4 so that these gases will rise in the part of the tank 1 under the plate 4. They then pass along the bottom of the plate 4 into the tower section 8. Under these conditions, excellent utilization of the total heat of the combustion gases is attained, i.e., a transfer of about or more of the usable heat from the gases to the liquid being heated.

The burner 13 shown in FIGS. 1 and 2, with its dual burner structure, is shown in FIG. 12. This burner comprises a central pilot tube 69 which is supplied with a fuel gas via the pilot gas tube 52. Pilot air is supplied via the pilot air pipe 70 into the pilot distributing chamber 51. The gases are ignited by an electrical igniter of conventional structure, (not shown) in the pilot tube and issued from the lower end of the pilot tube.

Around the central pilot tube 69 are a plurality of concentric, spaced tubes defining a series of passages. The annular passage 71 adjacent the pilot tube is an air supply passage for the inner burner, which is supplied to said passage through the air supply pipe 72 for the inner burner. Fuel gas is supplied to the inner burner through gas supply pipe 73 and flows through the inner burner gas supply passage 74 adjacent the air supply passage 71. The inner burner air and gas flow through the inner burner distributor head 49 without mixing and issue from the burner plate 19 as concentric streams which igniteupon mixing.

The lower end of the inner burner distributor head 49 has a flange 75 which is bolted to the flange 76 at the upper end of the outer burner distributor head 50. There is a ring-shaped wall 77 extending across the upper end of the inner burner distributor head 49 between the pilot tube 69 and the next adjacent concentric tube to divide the inner burner distributor head 49 from the pilot burner distributor head 51. The upper end of the gas supply passage 74 has a ring-shaped closure wall 78 closing oif the upper end of this passage.

The outer burner is built about the inner burner with the outer burner distributor head 50 and its air and fuel gas passages surrounding the inner burner. Gas is Supplied to the innermost passage. 80 of the outer burner through gas supply pipe 79 in the distributor head 50. Air is supplied to the distributor head 50 by the air supply pipe 82 and flows through the outermost annular passage 83, forming an envelope of air which burns with the gas discharged from the fuel gas passage 80 after they are discharged through the burner 19. The positioning of the air supply passage 83 as the outermost passage of the outer burner is essential to a smooth operating burner. The outermost air passage 83 is closed ofi at its upper end by the ring-shaped closure wall.

The inner and outer burners are concentric, independently operable burner units having a large range capacity of B.t.u. output. The inner burner has a lesser B.t.u. output capacity than the larger, outer burner. With this type of concentric burner relationship, the smaller inner burner can be ignited relatively smoothly by the ignited gases of the pilot tube. The inner burner, once ignited, canthen serve as the pilot burnerfor ignition of the higher B.t.u. capacity outer burner which is in surrounding relationship therewith. Each burner can be turned down, turned up or shut down independently of the other burner to give a readily variable range of B.t.u. output of the burner as a whole. The orifices for the air passages of the inner and outer burners are preferably large ports, while the orifices for the fuel gas passages in the burner plate are preferably relatively small orifices spaced closely together.

Various types of burner plates may be employed to provide varying amounts of air and combustible gas to be burned by the burner. For example, the size and/or number of the openings in the burner plates may be varied to provide the desired amount of gas supplied at the T burner plate. Also, the size of the ports may be varied to conform the amount of combustion-supporting gas, such as air, with the amount of gas being supplied to thereby provide maximum efiiciency of the burner. It

is, thus, possible to vary the B.t.u. output of the main burner or the pilot burner by merely changing the burner plate.

By way'of illustration, the pilot burner may be one having a capacity of approximately 5 10 B.t.u., and the outer or main burner may have a maximum output of about 10X 10 B.t.u. The outer or main burner may be used to add from 1x10 to 10x10 B.t.u. to the 5X10 B.t.u. pilot burner. Thus, in one unit there is a maximum capacity of 15x10 B.t.u. and a minimum capacity of 5 X10 B.t.u. Further, it is possible to cut the pilot burner back to a lesser B.t.u. output value, as for example, 2.5 X10 B.t.u.-giving a range in the capacity of heat supplied from this single burner from about 2.5 10 to 15x10 B.t.u. By providing an additional burner in surrounding relationship with the main burner, it is possible to achieve even much larger values in maximum B.t.u. output while still retaining the desirable features of smooth ignition and operation of the burner as a whole.

The foregoing values of B.t.u. outputare not to be construed as anything but illustrative of the invention herein described. The pilot burner may have a smaller or greater maximum B.t.u. output, and the outer or main burner may also have a smaller or larger B.t.u. output than the values given above by way of illustration. In the preferred practice of the invention, however, the maximum B.t.u. output of the outer burner will be substantially greater than the maximum B.t.u. output of the inwardly adjacent burner.

The embodiment of FIG. 7 is one especially adapted for use in the evaporation or condensation of a liquid by vaporization thereof. Since temperature control is not a significant factor in most evaporation processes, the temperature control mechanism and automatically responsive mechanical linkage for turning down or turning up the outer burner air and fuel gas flow can be omitted in most evaporating vessels. Structurally, the evaporating vessel of FIG. 7 is very similar to the heating vessel of FIGS. 1 and 2 with the temperature control regulator 35 and the butterfly valves 58, 59 and their associated parts omitted. In this embodiment, the burners are turned down and turned up by the manual control valves. Because the main structural change in the embodiment of FIG. 7 with respect to the embodiment. of FIGS. 1 and 2 lies in the liquid supply and discharge arrangement for the tank 1, only the lower portion of the tank has been illustrated. The remaining portions are similar to the parts illustrated in FIGS. 1 and 2 and, hence, need not be repeated.

In the evaporating vessel of FIG. 7, the liquid, such as water containing dissolved salts or the like,.is admitted to the tank 1 through the inlet pipe 84 connected by a union 85 to a manual valve 86. The solution is heated by gases discharged from the tube 23 beneath the level of the liquid. The concentrated solution is withdrawn through the outlet pipe 87, to which it is connected by a union 88 to the manual valve 99. -Tl1e submerged combustion burner 18 may be a dual combustion burner of the type illustrated in FIG. 12, or it may be a'combustion burner having only a single burner.

The embodiment of the invention illustrated-in FIGS.

8 and 9 is a vessel especially adapted to be used as an evaporating vessel. The liquid in the vessel is heatedby .direct heat exchange between hot combustion gases supplied to the vessel by a submerged combustion burner 90 of any suitable construction, e.g., a burner of the type illustrated in FIG. 12. The hot combustion gases issuing from the burner 90 pass from the combustion chamber 91 into a cylindrical leg 92. The hot combustion gases municating with the cylindrical tank 96. The ends of the evaporating vessel are closed by end walls 99, 100.

The top of the semicylindrical section 98 is closed by a flat plate 101 and includes an extension segment 102 extending into the cylindrical tank 96. This extension 102 divides the tank 96 into upper and lower semicylindrieal sections for a major part of the length of the cylindrical tank 96.

The evaporating vessel has a rectilinear gas and vapor chamber 163 which communicates with the end of the cylindrical tank 95 and the portion above the plate 1191 and its extension 102. The chamber 163 is separated from the semicylindrical segment of the evaporating vessel by the plate 161. The chamber 103 is defined by rectangular side walls 16d, 165, a rectangular end wall 1116, and end wall 107 having a lower end of arcuate curvature corresponding with the curvature of cylindrical tank 96, and a rectangular top wall 1113. Gases and vapors are discharged from the chamber 193 through the gas and vapor outlet 109, which can be connected-to suitable piping for further conveyance of the gases and vapors.

The liquid to be evaporated can be admitted at any convenient place. For sake of illustration, the liquid inlet pipe 119 is shown in FIG. 9 at a location in the end wall 1%. A drain pipe for withdrawing the concentrated liquid after the desired degree of evaporation has taken place is located in the lower part of the evaporating vessel at any convenient point. For sake of illustration, the drain pipe 11 is shown in FIG. 9 at a location in the lowest point in the end wall 99. It may also be located in the lowest part of the end wall 10901 in the bottom of the tank 95 or the semicylindrical section 98.

The evaporating vessel of FIGS. 8 and 9 provides both indirect heat exchange and direct heat exchange between the liquid in the vessel and the heat of the hot combustion gase The combustion chamber M, the cylindrical leg 92, and the tubes 93, 94 are submerged in the liquid and are heated by the hot gases passing therethrough. The walls of these parts in contact with the liquid provide an indirect heat exchange. The hot gases issuing from the orifices of tubes 93, 94 pass upwardly through the liquid in the evaporating vessel and give direct heat exchange between the hot gases and the liquid. The passage of the hot gases to the gas and vapor chamber'is lengthened by the provision of the divider plate extension 102, which extends across the cylindrical tank 95 and has a length at least equal to and preferably exceeding the length of extension of the tubes 93, 94 into the cylindrical tank E6. The plate 161 and its extension 192 stop the gases in the gas space above the liquid from rising directly upwardly into the gas and vapor chamber. The gases must travel along the undersurface of the plate 101 and its extension 192 to the end of the extension 162 before they can rise and be discharged through the gas and vapor chamber 103. Thus, the release space in which entrained liquid can be released from the gases and vapors is lengthened by the tortuous path the gases must take between the upper surface of the liquid and the gas and vapor chamber.

The embodiment of the invention shown in FIGS. 10 and 11 operates on similar principles to the embodiment of FIGS. 8 and 9. This embodiment of the invention comprises a submerged combustion burner 112 of any suitable construction. The vessel comprises a cylindrical tank 113 having a short semicylindrical extension 115. The ends of the vessel are closed off and end walls 116 and the top of the semicylind-rical extension 115 are closed by a fiat top wall 114. The top wall 114 has an extension plate 117 which extends a substantial distance into cylindrical tank 113 and divides it into upper and lower segments for a substantial distance of the length of the cylindrical tank 113.

This liquid heating vessel has a gas and vapor chamber 118 of generally rectilinear shape. The gas and vapor chamber 118 is defined by rectangular side Walls 119, 121 end walls 121, 122, each having an arcuate bottom edge corresponding to the curvature of the cylindrical Wall of the tank 113, and a rectangular top wall 122. Gases and vapors are discharged from the chamber 118 through a vent pipe 123 in the top wall 122. The liquid heating vessel of FIGS. 10 and 11 may have, if desired, temperature control instruments for regulating the heat output of the submerged combustion burner, such as those described above with respect to FIGS. 1 and 2.

The liquid to be concentrated is supplied to the vessel through the liquid supply pipe 124 mounted in and extending through the top wall 114. The submerged cornbustion burner 112 is also mounted in and extends through top wall 114 and its combustion chamber has a horizontal extension leg extending into the evaporating vessel below the extension plate 117. The hot combustion gases discharge into the liquid through gas orifices 126 located along the underside of the extension leg 125. The liquid can be withdrawn from the tank 113 at the desired time through the discharge pipe 127. The vessel is supported on saddles 128.

The hot combustion gases issuing from the burner chamber of burner 112 pass through the horizontal leg 125. The burner chamber and the horizontal leg are submerged in the liquid being heated. They heat the walls of these members, which, in turn, provide indirect heat exchange between the liquid and the hot combustion gases which heat these walls. There is further heat exchange between the hot combustion gases and the liquid by direct contact of the hot combustion gases issuing from the orifices or ports 126, which gases rise through the liquid, and travel along the undersurface of the plate 114 and its extension 117. When the gases reach the end of the plate extension 117, they pass upwardly into the upper portion of the cylindrical tank 113, after which the gases and Vapors from the liquid being concentrated are vented through the gas and vapor chamber 118 and the vent pipe 123.

The evaporating vessels of the embodiments of FIGS. 7, 8 and 9, ordinarily will not need temperature control instruments for regulating the heat output of the submerged burner inasmuch as the primary objective of these embodiments is to provide an apparatus for concentrating the liquid with highly efiicient heat exchange between the hot gases and the liquid. Where, however, the liquid is being concentrated is susceptible to decomposition or the like, a liquid temperature control of the type shown for the embodiment of FIGS. 1 and 2 may be employed. Hence, the gas flow control to the combustion burners for these embodiments of the invention may be either a manual type control or an automatic type control. An automatic type control for the dual combustion burner of FIG. 12 is shown in the diagrammatic view of FIG. 13 wherein fuel gas is supplied to the burner through the main fuel gas supply pipe 130 containing a shut-off valve 131, a reducer 152, a line pressure regulator 133 and a reducer 134.

Branching oil the fuel gas main supply pipe 130 after the reducer 134 is a fuel gas pipe 135 containing a reducer 136, a line pressure regulator 137 and a reducer 138.

.The pipe 135 has an extension continuation 139 containing a motor operated on off line control valve 140. The pipe 139 also has a butterfly control valve 141 and an orifice plate 142. The pipe 13? supplies fuel gas to the outer burner 59 under the control of the on-off valve and the volume-regulating butterfly valve 141.

The fuel gas supply pipe 135 is connected with a branch, fuel gas pipe 143 which contains an on-otl solenoid valve 144 and a volume control valve 145. The pipe 143 also has an orifice plate 146. Fuel gas is supplied through pipe 143 under the control of valves 144 and 145 to the inner burner 49.

The fuel gas supply pipe 130 also has connected therewith a fuel gas branch pipe 147 containing a line pressure regulator 148, a solenoid, on-oif valve 150, reducers 149, 151 and .153 and a flow meter 152. Fuel gas is supplied through the branch pipe 147 to the distributing head 51 of the pilot burner.

The combustion air is supplied from the blower 154 through the main air supply pipe 155. The volume of air supplied to the outer burner 50 is controlled by the butterfly valve 156.

nected therewith ahead of the butterfly valve 156. The air flow through the branch pipe 157 may be controlled by a manually adjustable valve 158. The branch pipe 157 also contains an orifice-plate 159. Combustion air for the inner burner 49 is supplied to the distributing head of this burner via the branch pipe 157.

The main air supply pipe is also connected to another branch pipe 160, through which the air flows via'a flow meter 161 and pipe 164 connected thereto to the distributing head 51 for the pilot burner. The branch pipe 160 has a branch line 162 conected thereto, which branch line, in turn, has a still further branch line 163. These branch lines 162 and 163 are connected, respectively, with the line pressure regulators 137 and 148 to maintain the line pressure in the'fuel gas supply pipes in the desired relationship with the air pressure in the air supply line. Should there be a malfunction of the blower 154, which results in zero or very low pressure in the air supply pipes, fuel gas flow to the burner will be cut olf by the regulators 137, 148 to avoid dangerous accumulation of fuel gas in the apparatus.

The butterfly valves 141 and 146 are interconnected by a mechanical linkage shown diagrammatically by the broken line designated by the numeral 164. This mechanical linkage is operated by a liquid temperature sensitive mechanism to adjust the quantity of gas and air flowing through the supply pipes to the outer burner. This mechanicallinkage and associated, temperature responsive mechanism may be of the character described with reference to the embodiment of FIGS. '1 and 2.

The various illustrated embodiments of the invention have a number of structural similarities. In each case, the liquid is heated by indirect heat exchange through the walls of the combustion chamber and combustion gasconveying'means located below the surface of the liquid in the vessel and by direct heat exchange with the hot combustion gases discharged into the liquid from a plurality of small. orifices in a submerged tube or tubes. The "gases and vapors are discharged from a vapor and gas chamber extending above the liquid-holding tank a suflicient distance to preclude substantial. entrainment of liquid particles (to be contrasted with vapors from the liquid). The combustion gases are discharged into the liquid below a plate, which may be either a top plate of the liquid-holding tank or a substantially horizontal divider plate therein, so that, when the vessels are operated with. the liquid level below the level of the said plate, the structures of the illustrated embodiments have the advantage of improved removal of entrained liquid particles from the gases and vapors because they must travel under the plate, and in saidcases also above the plate, before they reach the vapor and gas chamber. By such structure, the release space in which the entrained liquid is re-' leased from the gases is extended over a substantial length, i.e., the space in which they flow through the liquid-holding tank plus the space in the vapor and gas chamber. These spaces must be sufficiently large to provide a low enough gas velocity to allow the entrained liquid to be released from the gases.

A submerged combustion apparatus of the type characterized above has been disclosed previously in our copending application Serial No. 192,768, filed May 7, 1962, which in turn is a continuation-in-part of application Serial No. 21,310, filed April, 11, 1960, now abandoned, the disclosure of which was incorporated by refernce in said application Serial No. 192,768.

The towers 8 and 118 can contain packing such as Raschig rings, spiral rings, or the like, through which the liquid introduced into the tower gravitates. This aids in the removal of entrained liquid in the combustion gases discharged through the tower and also provides a better surface contact between the incoming liquid and the vapors carried with the combustion gases so that these vapors will condense and be returned to the body of liquid 10 along with the liquid gravitating through the packed tower. In liquid heating apparatus, as contrasted with evaporating apparatus, the tower packing has the advantage of minimizing liquid loss through vaporization. Vaporization is not a desired characteristic in a liquid heating apparatus, whereas in evaporating apparatus, vaporization is desired.

A submerged combustion burner of the. type described herein has been disclosed in our copending application Serial No. 731,823, filed April 29, 1958, and our copending application Serial No. 192,768, filed May 7, 1962. In said applications, we have disclosed a multiple submerged combustion burner comprising a plurality of concentric tubes definingat least three combustion supporting gas passages and at least'three fuel passages, the said passages being paired so that each fuel passage is adjacent a com-- bustion supporting gas passage but not necessarily in the same sequence, the innermost tubes defining a pilot burner, the next pair of tubes defining a first burner, the next pair of tubes defining a second burner, and successive pairs of tubes, if'any, defining additional burners, means for supplying pilot fuel and pilot combustion supporting gas to said pilot burner, distributing head means on said burner for supplying fuel and combustion supporting gas separatelyto one end of each of said first burner and successive burners, a burner plate with holes therein at the opposite end of each of said fuel passages of said first burner and successive burners, the passages for the combustion supporting gas each having a relatively unrestricted open endadjacent each said burner plate with openings therein larger than the holes in said burner plate, said passages for fuel and combustion supporting gas of said first and successive burners being of substantially the same length, a flange extending outwardly on the outermost tube of said burner, a combustion chamber secured to said flange and surrounding the lower part of said burner in spaced relation thereto, said combustion chamber extending beyond said burner plates and having an opening therein of sufiiciently small size to provide a back pressure in said combustion chamber when said burner is in operation, and means for variably controlling said first and successive burners with respect to one another. The combustion chamber is sized to allow all fuel to burn before the products of combustion pass through the opening in the combustion chamber into the solution. In a dual burnerof the type described in order to achieve optimum smoothness of operation the burner tubes from the center should contain pilot, air, gas, gas and air. It is essential to have separate and independent passages for the fuel supplies (e.g., natural gas) and combustion supporting gas (e.g. air). It is not necessary to use the same gaseous fuel for both burners of a dual burner. Two different gaseousfuels can be used,

In a dual burner of the type described, the'mixing of gaseous fuel and air depends on velocity, size and placement of gas orifices or holes in the burner plate at full capacity. The capacity of the burner is set by the burner plate in each tube except the pilot where there is no burner plate. Either the fuel of the first burner or that of the second burner can be reduced to zero after starting at full capacity but both burners fuels cannot be turned down equally and simultaneously or the burners will go out where no other conditions are varied.

The illustrated embodiments are those which we now consider to be the best modes for practice of the generic principles and concepts of the invention. The invention includes within its spirit and scope, as defined in the appended claims, still other embodiments thereof.

The invention is hereby claimed as follows:

1. -A combustion apparatus comprising:

(a) a pilot tube,

(b) a first pair of concentric tubes about said pilot tube, defining a pair of annular passageways, one for fuel and one for combustion supporting gas, said tubes making up an inner burner,

) the outer ends of each of said passageways for combustion supporting gas of (b) and (c) having openings therein of larger total cross sectional area than the total cross sectional area of the holes in each of said burner plates of (b) and (0), respectively,

( a flange about the outermost tube,

(21) a combustion chamber secured in liquid tight engagement with said flange, said combustion chamber being tubular, surrounding the outer ends of (a), (b) and (c), and extending beyond the ends of (a), (b), and (c), said combustion chamber having an opening at its outer end of smaller cross sectional area than the cross sectional area of said combustion chamber, the size of said combustion chamber and said opening being such as to produce back pressure within said chamber when said burner is in operation, and

(i) means for variably controlling the introduction of fuel and combustion supporting gas to (b) and (c).

2. A combustion apparatus as claimed in claim 1 in which the arrangement of tubes (a), (b) and (c) is pilot, air, gas, gas, air from the center outward.

3. A combustion apparatus as claimed in claim 1 .in which (i) comprises means connected to control means for the introduction of fuel and to control means for the introduction of combustion supporting gas forrmaintaining a predetermined differential in the rate of introduction of fuel and combustion supporting gas to at least one of the burners (b) and (c).

d. A combustion apparatus comprising:

(a) a pilot tube,

(b) a second tube about said pilot tube and defining.

therebetween an air passage, a third tube about said second tube and defining therebetween a fuel gas conveying, annular passage, said tubes making up an inner burner,

(c) a fourth tube mounted concentrically about said 7 passages defining an independently operable, outer burner, and

(f) power-operated means for turning down and turning up the air and gas flow to said outer burner passages at a greater turn down ratio of said fuel gas than said air and, correspondingly, a greater turn up ratio of said gas than said air.

5. A combustion apparatus as claimed in claim 4 wherein said power-operated means comprises a motor, an arm operatively associated with and activated by said motor, pipes connected to said distributor head means for respectively supplying air and fuel gas to said distributor head means, butterfly valves in each of said air and fuel gas pipes, supplying air and fuel gas to said outer burner, a link arm connected to and rotatable with the valve plate of each butterfly valve, said link arm which is connected to the plate of the butterfly valve in the air pipe being longer than the link arm which is connected to the rotatable plate of the butterfly valve in said fuel gas pipe, a connecting arm connecting said last-mentioned link arms, and a second connecting arm connecting said connected link arms with the arm of said motor, whereby activation of the arm of said motor causes the plates of said butterfly valves to rotate with a lesser degree of rotation of the plate of the butterfly valve in said air pipe than the plate of the butterfly valve in the fuel gas pipe.

6. A combustion apparatus as claimed in claim 1 wherein said means for variably controlling the introduction of fuel and combustion supporting gas to (c) comprises valve means for controlling the quantities of the fuel gas and combustion supporting gas fed to said second burner, liquid temperature control means, and means activated by said liquid temperature control means and interconnected to said valve means to provide a greater turn down of the fuel gas supply to said burner than the turn down of said combustion supporting gas supplied to said burner and, correspondingly, a greater turn up of the fuel gas supply to said burner than the turn up of the combustion supporting gas supplied to said burner when the fuel gas flow and combustion supporting gas flow to said burner is adjusted in response to said temperature control means.

References Cited by the Examiner UNITED STATES PATENTS 227,852' 5/80 Snow et al 158-110 1,484,107 2/24 Zander 158-1l0 X 2,118,479 5/38 See et al 126360 2,408,114 9/46 Urquhart 1581 19 2,797,746 7/57 Bourek et a1 158119 2,823,740 2/58 Morck 158-119 2,900,975 8/59 Northcott 12636O 2,911,035 11/59 Nieman et a1. 15899 JAMES W. WESTHAVER, Primary Examiner. 

1. A COMBUSTION APPARATUS COMPRISING (A) A PILOT TUBE, (B) A FIRST PAIR OF CONCENTRIC TUBES ABOUT SAID PILOT TUBE, DEFINING A PAIR OF ANNULAR PASSAGEWAYS, ONE FOR FUEL AND ONE FOR COMBUSTION SUPPORTING GAS, SAID TUBES MAKING UP OF CONCENTRC BURNER, (C) A SECOND PAIR OF CONCENTRIC TUBES ABOUT SAID FIRST PAIR OF TUBES, DEFINING A SECOND PAIR OF ANNULAR PASSAGEWAYS, ONE FOR FUEL AND ONE FOR COMBUSTION SUPPORTING GAS, SAID TUBES MAKING UP A SECOND BURNER, (D) MEANS FOR INTRODUCING FUEL AND COMBUSTION SUPPORTING GAS SEPARATELY TO (A), (B) AND (C), SAID MEANS COMPRISING A DISTRIBUTOR HEAD ON (B) AND (C), (E) A BURNER PLATE AT THE OUTER END OF EACH OF THE FUEL PASSAGEWAYS OF (B) AND (C), SAID BURNER PLATE HAVING HOLES THEREIN, (F) THE OUTER ENDS OF EACH OF SAID PASSAGEWAYS FOR COMBUSTION SUPPORTING GAS OF (B) AND (C) HAVING OPENINGS THEREIN OF LARGER TOTAL CROSS SECTIONAL AREA THAN THE TOTAL CROSS SECTIONAL AREA OF THE HOLES IN EACH OF SAID BURNER PLATES OF (B) AND (C), RESPECTIVELY, (G) A FLANGE ABOUT THE OUTERMOST TUBE, 